Tesis sobre el tema "Méthode à densité"
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Youndje, Elie. "Estimation non paramétrique de la densité conditionnelle par la méthode du noyau". Rouen, 1993. http://www.theses.fr/1993ROUES011.
Aucejo-Galindo, Vicente. "Méthode tensorielle générale pour une modélisation multiphysique de dispositifs magnétomécaniques rapides". Thesis, Metz, 2010. http://www.theses.fr/2010METZ028S/document.
Currently the goal of knowledge magnetomechanical devices is completed by means of several complementary approaches. On one hand the physical approach with mathematical formulations of magnetic forces. On the other hand, multiphysics approaches to achieve a deeper insight and more real, physical phenomena associated with interactions that act in the devices. And finally, the interdisciplinary approach that takes into account the lifecycle of the product, so called eco-design. A design of a ultra fast micromotor with induced magnetization and axial flux is presented in this paper with the physical approach showing the restrictions thereof. Accordingly therefore, the physical approach, a new tensor method is developed as a general contribution to a multiphysics modeling of magnetomechanical devices, bringing together the various numerical formulations of magnetic forces. A characterization of the new tensor is presented and applied to calculate the forces on bodies in contact
Beaucamp, Sylvain. "Méthode de calcul des densités et des enthalpies de cristaux ioniques moléculaires". Tours, 2004. http://www.theses.fr/2004TOUR4052.
Performances of energetic materials depend on their density, their solid-state of formation and their stoechiometry. The aim of this works is the development of model to estimate the density and the solid-state of formation of energetic salts, X-N+ NO[-3], from their developed formulate. Model using additive volumes for charges groupes is developed to predict crystal densities of molecular salts. On the one hand, the group contribution method of Ammon and Mitchell is extended molecular salts. On the other hand, a less empirical contribution method is presented. Solid state-heat of formation of a molecular salts depend on the anthalpie of the isolated ions and the cohesive energy of the crystal salts. The estimate the cohesive energy two approach are developed : a semi-empirical model using descriptors computed on isolated ions and the crystal packing of virtual crystal salts of ions. Moreover, implementation of the symetry-constrained in the self consistent charges density functional tight binbing model is developped. This routine may riffine virtual salts structure obtained by packing model. The last part shows applications of previous developed models to the prediction of the solid state of formation of nitrate salts
Carbone, Mathieu. "Efficacité, généricité et praticabilité de l'attaque par information mutuelle utilisant la méthode d'estimation de densité par noyau". Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS087.
Nowadays, Side-Channel Analysis (SCA) are easy-to-implement whilst powerful attacks against cryptographic implementations posing a serious threat to the security of cryptosystems for the designers. Indeed, the execution of cryptographic algorithms unvoidably leaks information about internally manipulated data of the cryptosystem through side-channels (time, temperature, power consumption, electromagnetic emanations, etc), for which some of them are sensible(depending on the secret key). One of the most important SCA steps for an adversary is to quantify the dependency between the measured side-channel leakage and an assumed leakage model using a statistical tool, also called distinguisher, in order to find an estimation of the secret key. In the SCA literature, a plethora of distinguishers have been proposed. This thesis focuses on Mutual Information (MI) based attacks, the so-called Mutual Information Analysis (MIA) and proposes to fill the gap of the major practical issue consisting in estimating MI index which itself requires the estimation of underlying distributions. Investigations are conducted using the popular statistical technique for estimating the underlying density distribution with minimal assumptions: Kernel Density Estimation (KDE). First, a bandwidth selection scheme based on an adaptivity criterion is proposed. This criterion is specific to SCA.As a result, an in-depth analysis is conducted in order to provide a guideline to make MIA efficient and generic with respect to this tuning hyperparameter but also to establish which attack context (connected to the statistical moment of leakage) is favorable of MIA. Then, we address another issue of the kernel-based MIA lying in the computational burden through a so-called Dual-Tree algorithm allowing fast evaluations of 'pair-wise` kernel functions. We also showed that MIA running into the frequency domain is really effective and fast when combined with the use of an accurate frequency leakage model. Additionally, we suggested an extension of an existing method to detect leakage embedded on higher-order statistical moments
Thauvoye, Christophe. "Simulation numérique d'écoulements turbulents réactifs par une méthode hybride à fonction densité de probabilité transportée". Poitiers, 2005. http://www.theses.fr/2005POIT2276.
This work concerns the field of numerical simulation of turbulent reactive flows. The aim of this work is to study a hybrid method based on the use of a lagrangian transported Probability Density Function (PDF) method coupled with a eulerian method which solves the Reynolds Averaged Navier-Stokes equations (R. A. N. S). The first part is devoted to the description of the RANS and the transported PDF methods. The latter is more precisely detailed : it allows to highlight both advantages and drawbacks of the two approaches. In this context, we will develop all the aspects related to the modelling and resolution of the transported joint PDF equation. Its resolution generally uses a Monte-Carlo numerical simulation. We also show how the statistical nature of Monte-Carlo methods induces numerical difficulties, which led to the development of hybrid methods associating RANS method with a transported PDF approach. In the second part of this study, theoretical and numerical aspects of the hybrid methods are detailed, and more precisely the PEUL+ model developed at ONERA. A new – instationary – way of coupling is proposed. It improves the stability and precision of the model in comparison with the stationary way of coupling. It is then tested and validated on two configurations : a methane-air nonpremixed flame stabilised by a piloted flame ; and a premixed flame in a sudden symmetric plane expansion
Benkaci-Ali, Hassene. "Optimisation des performances d'un ondulateur à modulation de densité d'impulsion modélisation mathématique et méthode génétique". Thèse, Université du Québec à Trois-Rivières, 2013. http://depot-e.uqtr.ca/6977/1/030596182.pdf.
Bechereau, Marie. "Élaboration de méthodes Lattice Boltzmann pour les écoulements bifluides à ratio de densité arbitraire". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN059/document.
Two-fluid extensions of Lattice Boltzmann methods with free boundaries usually consider ``microscopic'' pseudopotential interface models. In this paper, we rather propose an interface-capturing Lattice Boltzmann approach where the mass fraction variable is considered as an unknown and is advected. Several works have reported the difficulties of LBM methods to deal with such two-fluid systems especially for high-density ratio configurations. This is due to the mixing nature of LBM, as with Flux vector splitting approaches for Finite Volume methods. We here give another explanation of the lack of numerical diffusion of Lattice Boltzmann approaches to accurately capture contact discontinuities. To fix the problem, we propose an arbitrary Lagrangian-Eulerian (ALE) formulation of Lattice-Boltzmann methods. In the Lagrangian limit, it allows for a proper separated treatment of pressure waves and advection phenomenon. After the ALE solution, a remapping (advection) procedure is necessary to project the variables onto the Eulerian Lattice-Boltzmann grid.We explain how to derive this remapping procedure in order to get second-order accuracy and achieve sharp stable oscillation-free interfaces. It has been shown that mass fractions variables satisfy a local discrete maximum principle and thus stay in the range $[0,1]$. The theory is supported by numerical computations of rising bubbles (without taking into account surface tension at this current state of development).Even if our methods are currently used for inviscid flows (Euler equations) by projecting the discrete distributions onto equilibrium ones at each time step, we believe that it is possible to extend the framework formulation for multifluid viscous problems. This will be at the aim of a next work
Jerier, Jean-François. "Modélisation de la compression haute densité des poudres métalliques ductiles par la méthode des éléments discrets". Grenoble 1, 2009. http://www.theses.fr/2009GRE10242.
This Ph. D. Manuscript synthesises three years of research dedicated to numerical and theoretical studies of high density powder compaction. During cold compaction process, the compaction stage is among the most sensitive powder metallurgy’s stages, because it has a strong impact on the mechanical properties of the final part. It is necessary to find a numerical approach to control and to optimize the high density powder compaction (density value above 0:9). We propose to model by the discrete element method the behaviour of powder which is observed experimentally under different loading paths. To date, the discrete element simulations are not able to model the powder compaction for high density values (density is limited at 0:85). To go beyond this limit, we present a contact model implemented into a discrete element open-source software (Yade). This new contact model is based on a normal contact law which integrates in its expression the local density parameter. This new local variable takes into account the incompressibility of the material which appears at density values above 0:85. In order to realize more realistic simulations, a new geometric algorithm to generate polydisperse sphere packings is developed. This new numerical tool is able to generate very fast large sphere assemblies with different properties controlled by the user as: density distribution, the minimal and maximal size of spheres. With the contact model capable of reproducing the granular interaction up to high density value and the geometric algorithm which generates sphere assemblies similar to powder, we realize simulations of isostatic and closed die compaction for various types of powder (copper, aluminium, iron). The results are directly compared with those obtained by multi-particle finite element method and by experimental tests. These comparisons allow to validate and test the robustness of the contact model developed here. Finally, we investigate the evolution of aluminium powder assembly composed with an initial graded density distribution during the closed die compaction
Durance, Loïc. "Développement d'une méthode de stérilisation par la chaleur de solutions injectables conditionnées en polyéthylène basse densité". Amiens, 2003. http://www.theses.fr/2003AMIED003.
The solutions for injection are usually packaged in glass flasks and sterilised by moist steam. Is the current tendency to substitute glass by the plastic because it reduce the obstruction of conditioning while increasing its shock-proofness and allows a board elimination of the wastes by incineration. Only some plastics meet both public health regulations and ecological requirements. Among them, low density polyethylene (LDPE) offers various advantages. It possesses virtually no additive, which limits the interaction hazards between plastic and chemical substances used in injection preparations. Its destruction does not bring chlorine-containing waste or other toxic matter into the atmosphere. Moreover, it is fully adapted to the various manufacturing technologies for large-scale production as the blow-fill-an-seal. However, the temperature value admitted for sterilisation is 121°C, whereas LDPE exhibits a melting point at about 117°C. Therfore, we have developped an alternative cycle of sterilisation based on F0 concept at a temperature lower than 121°C and such as it respected the LDPE containers integrity. The efficiency on the micro-organisms destruction have been calculated aid of stocks spores of Bacillus Stearothermophilus introduced into the recipients which contained water for injection as base solution. The sterilised products have been followed throughout this period. The information obtained by this work have the aim of documenting a manufacturing authorization file about products for injection for its recording with the benefit of a pharmaceutical industry of Amiens
Aucejo-Galindo, Vicente. "Méthode tensorielle générale pour une modélisation multiphysique de dispositifs magnétomécaniques rapides". Electronic Thesis or Diss., Metz, 2010. http://www.theses.fr/2010METZ028S.
Currently the goal of knowledge magnetomechanical devices is completed by means of several complementary approaches. On one hand the physical approach with mathematical formulations of magnetic forces. On the other hand, multiphysics approaches to achieve a deeper insight and more real, physical phenomena associated with interactions that act in the devices. And finally, the interdisciplinary approach that takes into account the lifecycle of the product, so called eco-design. A design of a ultra fast micromotor with induced magnetization and axial flux is presented in this paper with the physical approach showing the restrictions thereof. Accordingly therefore, the physical approach, a new tensor method is developed as a general contribution to a multiphysics modeling of magnetomechanical devices, bringing together the various numerical formulations of magnetic forces. A characterization of the new tensor is presented and applied to calculate the forces on bodies in contact
Mourad, Nahia. "Fondements mathématiques et numériques de la méthode des pseudo-potentiels". Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1024/document.
The contributions of this thesis consist of three main results. The first result is concerned with analytic perturbation theory for Kohn-Sham type models. We prove, under some technical conditions, the existence, uniqueness and analyticity of the perturbed reduced Hartree-Fock ground state density matrix for regular perturbations arising from an external potential. Our analysis encompasses the case when the Fermi level of the unperturbed ground state is a degenerate eigenvalue of the mean-field operator and the frontier orbitals are partially occupied. The second result is concerned with the mathematical construction of pseudo potentials for Kohn-Sham models. We define a set of admissible semi local norm-conserving pseudo potentials of given local Sobolev regularity and prove that this set is non-empty and closed for an appropriate topology. This allows us to propose a new way to construct pseudo potentials, which consists in optimizing on the latter set some criterion taking into account both smoothness and transferability requirements. The third result is a numerical study of the reduced Hartree-Fock model of atoms. We propose a discretization method and an algorithm to solve numerically the Kohn-Sham equations for an atom subjected to a cylindrically-symmetric external potential. We report the computed occupied energy levels and the occupation numbers for all the atoms of the four first rows of the periodic table and consider the case of an atom subjected to a uniform electric-field
Cotoni, Vincent. "Modélisation de phénomènes vibroacoustiques en moyennes et hautes fréquences par méthode énergétique locale". Ecully, Ecole centrale de Lyon, 2001. http://www.theses.fr/2001ECDL0004.
This study describes a local power flow method used for solving vibroacoustic problems. The sound radiation of plane structures and the sound transmission through plane structures are studied and the sound radiation of curved structures is partially investigated. The present approach is dedicated to the middle and high frequency range where the locality principle may be used to calculate a system by solving several local canonical problems encountered in the whole system. The originality of the model is the use of energy quantities such as energy density and power flow. A local power balance is thus derived for each canonical problem. Considering the high frequency assumption that elementary waves describing the vibratory response are uncorrelated, the linear superposition principle is then applied on local energy solutions in order to compute the complete system. Several local energy formulations previously developed and called Méthode Energétique Simplifiée (Simplified Energy Method) are investigated. The particularity of the vibroacoustic coupling is the consideration of diffraction phenomena encountered in power exchanges. Thus, this work is an extension of existing local energy approaches
Lembarki, Abderrahim. "Développement de fonctionnelles corrigées du gradient en théorie de la fonctionnelle de la densité". Lyon 1, 1994. http://www.theses.fr/1994LYO10340.
Mahieu, Joris. "Cycloimmonium ylure : détermination structurale par la méthode de la fonctionnelle de la densité, dynamique harmonique et mécanique moléculaire". Littoral, 2002. http://www.theses.fr/2002DUNK0073.
The cycloimmonium ylides are very important intermediates in synthesis of azaheterocyclic compounds and ylidic polymers with specifically properties. In this paper dealt on structural determination using theoretical methods. The dicyano-pyridium methylide has been chosen as model for the cycloimmonium ylides, taking in account its structure and the corresponding experimental data. Firstly, we have found that the semi empirical AM1 and PM3, together with DFT procedure, are appropriate methods in the characterization of this type of molecules. This is in a good agreement with the x-ray diffraction measurements. Next, we have proposed a modified forces field parametrization in order to extend the structural determination for more complex ylidic systems
Hervé, Lionel. "Mesures de la composition corporelle et de la densité minérale osseuse par une méthode d'absorptiométrie X multi-énergie". Université Joseph Fourier (Grenoble), 2003. http://www.theses.fr/2003GRE10007.
Habbou, Abderrahim. "Densité électronique de déformation par la méthode X-X et structures cristallines de métalloporphyrines des groupes 13 et 14". Nancy 1, 1990. http://www.theses.fr/1990NAN10246.
Rouvière, Laurent. "Estimation de densité en dimension élevée et classification de courbes". Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2005. http://tel.archives-ouvertes.fr/tel-00011624.
La première partie, intitulée compléments sur les histogrammes modifiés, est composée de deux chapitres consacrés l'étude d'une famille d'estimateurs non paramétriques de la densité, les histogrammes modifiés, connus pour posséder de bonnes propriétés de convergence au sens des critères de la théorie de l'information. Dans le premier chapitre, ces estimateurs sont envisagés comme des systèmes dynamiques espace d'états de dimension infinie. Le second chapitre est consacré l'étude de ces estimateurs pour des dimensions suprieures un.
La deuxième partie de la thèse, intituleé méthodes combinatoires en estimation de la densité, se divise en deux chapitres. Nous nous intéressons dans cette partie aux performances distance finie d'estimateurs de la densité sélectionnés à l'intérieur d'une famille d'estimateurs candidats, dont le cardinal n'est pas nécessairement fini. Dans le premier chapitre, nous étudions les performances de ces méthodes dans le cadre de la sélection des différents paramètres des histogrammes modifiés. Nous poursuivons, dans le deuxième chapitre, par la sélection d'estimateurs à noyau dont le paramètre de lissage s'adapte localement au point d'estimation et aux données.
Enfin, la troisième et dernière partie, plus appliquée et indépendante des précédentes, présente une nouvelle méthode permettant de classer des courbes partir d'une décomposition des observations dans des bases d'ondelettes.
Hamon, Abdellatif. "Estimation d'une densité de probabilité multidimensionnelle par dualité". Rouen, 2000. http://www.theses.fr/2000ROUES055.
Huang, Lorick. "EDS dirigées par des processus stables : Méthode paramétrix pour des estimées de densités et application aux algorithmes stochastiques". Sorbonne Paris Cité, 2015. https://theses.hal.science/tel-01180708.
Density Estimates for SDEs Driven by Tempered Stable Processes. We study a class of stochastic differential equations driven by a possibly tempered Lévy process, under mild conditions on the coefficients (Wilder continuity). We prove the well-posedness of the associated martingale problem as well as the existence of the density of the solution. Two sided heat kernel estimates are given as well. Our approach is based on the Parametrix series expansion. A Parametrix Approach for some Degenerate Stable Driven SDEs. We consider a stable driven degenerate stochastic differential equation, whose coeffi- cients satisfy a kind of weak Hôrmander condition. Under mild smoothness assumptions we prove the uniqueness of the martingale problem for the associated generator under some dimension constraints. Also, when the driving noise is scalar and tempered, we establish density bounds reflecting the multi-scale behavior of the process. A Multi-step Richardson-Romberg extrapolation method for stochastic approximation We obtain an expansion of the implicit weak discretization error for the target of stochastic approximation algorithms introduced and studied in [30]. This allows us to extend and develop the Richardson-Romberg extrapolation method for Monte Carlo linear estimator (introduced in [79] and deeply studied in [65]) to the framework of stochastic optimization by means of stochastic approximation algorithms. We notably apply the method to the estimation of the quantile of diffusion processes. Numerical results confirm the theoretical analysis and show a significant reduction in the initial computational cost
Vervisch, Luc. "Prise en compte d'effets de cinétique chimique dans les flammes de diffusion turbulentes par l'approche fonction densité de probabilité". Rouen, 1991. http://www.theses.fr/1991ROUES053.
Roques, Jérôme. "Modélisation de l'adsorption dissociative de molécules diatomiques sur des agrégats métalliques par la méthode de la fonctionnelle de la densité : comparaison avec les propriétés du massif et de la surface infinie". Toulouse, INPT, 2001. http://www.theses.fr/2001INPT010G.
Saadane, Ouafa. "Etude du silicium polymorphe hydrogéné en couches minces pour applications photovoltai͏̈ques". Paris 11, 2003. http://www.theses.fr/2003PA112143.
The work presented in this thesis is devoted to the study of the metastability in the hydrogenated polymorphous silicon (pm-Si:H). The pm-Si:H films deposited in a plasma regime close to the powder formation, which promoted the incorporation of nanocrystallites and/or clusters in amorphous matrix of the layers. Previous results have shown the promising potentiality of the pm-Si:H for photovoltaic conversion. The aim of this study is to bring a better comprehension between the structural and optoelectronic properties of pm-Si:H films prepared under different deposition conditions. We used various methods of characterizations, and in particular some electrical techniques of characterizations: measurements of conductivity and photoconductivity (constant photocourant method, modulated photocurrent, steady state photocarrier gratings)), which we coupled with methods of structural characterizations (Fourier transform infrared spectroscopy and hydrogen effusion experiments). We particularly studied the metastability of the pm-Si:H. After a systematic study of a large number of pm-Si:H films, we highlighted the deposition conditions which lead to films with good properties transport (high deposition rate, high and excellent stability of the ambipolar diffusion length of the minority carriers, better efficiency of the solar cells). A link between hydrogen bonding and transport properties is made that shows that to exhibit good transport properties the material has to present a peculiar microstructure revealed by the hydrogen bonding. However, the hydrogen bonding and/or content in this structure has to be adjusted via the deposition conditions to reach an optimum hydrogen incorporation leading to the best layers and the best solar cell devices
Bally, Benjamin. "Description des noyaux impairs à l'aide d'une méthode de fonctionnelle énergie de la densité à plusieurs états de référence". Phd thesis, Bordeaux, 2014. http://tel.archives-ouvertes.fr/tel-01023059.
Pollet, Rodolphe. "Développement et applications d'une méthode généralisant la Théorie de la fonctionnelle de la densité à plusieurs déterminants de Slater". Paris 6, 2001. http://www.theses.fr/2001PA066525.
Gallouj, Hassan. "Détermination et validation de champs de forces par la méthode de fonctionnelle de densité (DFT) pour des résidus amino acides aromatiques". Lille 1, 1999. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1999/50376-1999-145.pdf.
Pichon-Pesme, Virginie. "Étude de l'effet anomérique par analyse de la densité électronique". Nancy 1, 1986. http://www.theses.fr/1986NAN10088.
Couto-Barba, Laurent. "Contribution à la simulation du mélange turbulent par la schématisation de fonctions densité de probabilité". Pau, 2005. http://www.theses.fr/2005PAUU3014.
This thesis considers a method which simplifies the mixing at different levels, depending on turbulence length and time scales. The analysis is here restricted to the case of homogeneous and isotropic turbulent flows. The model is based on elementary fluid particles considered in their different levels of neighborhoods. For each vicinity level, a specific mixing model is applied. The approach takes into account - from small to high length scales - laminar diffusion (Fick diffusion process), internal mixing into fluid particle (Kerstein model, 1988), external mixing between fluid particles contained into a same eulerian volume (inspired from the LMSE model developpef by Dopazo, 1974, or from the Curl model,1963) and turbulent dispersion (where lagrangian moves are computed). An internal clock organizes the sequence of applications of the different models. Each one is applied instantaneously at different periodic times. Two different cases have been studied. The first case is the time evolution of mixing between two components initially introduced in two different areas. The numerical results have been compared to those of Direct Numerical Simulations by Eswaran & Pope (1988). The time evolution of Probability Density Functions, and the evolutions of variance, symetry coefficient and flatness coefficient have been compared. A parametrical study of the parameter governing the sequence of application of the different models has been performed. The second case considers thermal mixing layers emitted from one or two hot films placed inside a grid turbulence with uniform mean flow. Numerical results are in qualitative agreement with the experimental results by Warhaft (1984)
Elmeguenni, Mohamed. "Effet de la triaxialité sur le comportement et la rupture du polyéthylène haute densité : approches expérimentales et numériques". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10035.
In a first part of this thesis, an experimental approach based on macroscopic measurements and microscopic observations (SEM and OM) led to a better understanding of damage mechanisms in high density polyethylene (HDPE) and its stress triaxiality sensitivity. In order to examine higher stress triaxiality values, cracked samples were experimentally examined in a second part. Based on the obtained results, the relevance of the fracture mechanics concepts to characterize the fracture toughness of HDPE was critically discussed. The investigation was performed using two well-known approaches of the fracture mechanics – J-integral and EWF – using different specimen configurations (SENB, CT and DENT). To gain insight into the strain field around the crack tip, digital image correlation method was used. The third part was focused on the demonstration of the relevance of ductile damage models (based on the void volume evolution as indicator of damage) to predict the mechanical and damage behaviour of HDPE and that, until complete failure. A special attention was paid on the stress triaxiality effects. Two failure criteria using complementary approaches were examined. These approaches were found relevant in the case of HDPE. Indeed, a good agreement was found between the numerical simulations and the experimental results in terms of overall response of axisymmetric samples (true stress-strain-volumetric response) and of cracked samples (load-displacement response) and in terms of local response corresponding to kinematics fields
Tsikata, Sedina. "Fluctuations de densité électronique à petite échelle dans un propulseur à effet Hall, investigué par la méthode de diffusion collective". Phd thesis, Ecole Polytechnique X, 2009. http://tel.archives-ouvertes.fr/tel-00484027.
Elyeznasni, Nadia. "Interfaces entre liquides modèles non miscibles : étude parallèle par la dynamique moléculaire et par la méthode de la fonctionnelle de densité". Paris 12, 2007. http://www.theses.fr/2007PA120007.
Due to its importance in many phenomena in chemistry and biology. We present a study of the structure in the interface between two immiscible liquids by density-functional theory and molecular-dynamics calculations. The liquids are modeled by Lennard-Jones potentials, which achieve immiscibility by supressing the attractive interaction between unlike particles. The density profiles of the liquids display oscillations only in a limited part of the simple liquid-phase diagram (density, temperature). When approaching the liquid-vapor coexistence, a significant depletion appears while the layering behavior of the density profile vanishes. By analogy with the liquid-vapor interface and the analysis of the adsorption this behavior is suggested to be strongly related to the drying transition. We present also a study of intrinsic profils by molecular dynamics to schow capillary waves effects to damp oscillatory structure in the interface between immiscible liquids
Sahnoun, Riadh. "Processus de dissociation de composés organométalliques et simulation de l'effet de l'environnement par la méthode de la fonctionnelle de la densité". Toulouse, INPT, 1998. http://www.theses.fr/1998INPT015C.
Ayme, Fabien. "Développement d'une méthode énergétique pour l'évaluation expérimentale des flux acoustiques entrants dans les cavités d'avion". Phd thesis, Ecole Centrale de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00995861.
Dion, Charlotte. "Estimation non-paramétrique de la densité de variables aléatoires cachées". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAM031/document.
This thesis contains several nonparametric estimation procedures of a probability density function.In each case, the main difficulty lies in the fact that the variables of interest are not directly observed.The first part deals with a mixed linear model for which repeated observations are available.The second part focuses on stochastic differential equations with random effects. Many trajectories are observed continuously on the same time interval.The third part is in a full multiplicative noise framework.The parts of the thesis are connected by the same context of inverse problems and by a common problematic: the estimation of the density function of a hidden variable.In the first two parts the density of one or two random effects is estimated. In the third part the goal is to rebuild the density of the original variable from the noisy observations.Different global methods are used and lead to well competitive estimators: kernel estimators, projection estimators or estimators built from deconvolution.Parameter selection gives adaptive estimators and the integrated risks are bounded using a Talagrand concentration inequality.A simulation study for each proposed estimator highlights their performances.A neuronal dataset is investigated with the new procedures for stochastic differential equations developed in this work
Libengue, Dobele-kpoka Francial Giscard Baudin. "Méthode non-paramétrique des noyaux associés mixtes et applications". Thesis, Besançon, 2013. http://www.theses.fr/2013BESA2007/document.
We present in this thesis, the non-parametric approach using mixed associated kernels for densities withsupports being partially continuous and discrete. We first start by recalling the essential concepts of classical continuousand discrete kernel density estimators. We give the definition and characteristics of these estimators. We also recall thevarious technical for the choice of smoothing parameters and we revisit the problems of supports as well as a resolutionof the edge effects in the discrete case. Then, we describe a new method of continuous associated kernels for estimatingdensity with bounded support, which includes the classical continuous kernel method. We define the continuousassociated kernels and we propose the mode-dispersion for their construction. Moreover, we illustrate this on the nonclassicalassociated kernels of literature namely, beta and its extended version, gamma and its inverse, inverse Gaussianand its reciprocal, the Pareto kernel and the kernel lognormal. We subsequently examine the properties of the estimatorswhich are derived, specifically, the bias, variance and the pointwise and integrated mean squared errors. Then, wepropose an algorithm for reducing bias that we illustrate on these non-classical associated kernels. Some simulationsstudies are performed on three types of estimators lognormal kernels. Also, we study the asymptotic behavior of thecontinuous associated kernel estimators for density. We first show the pointwise weak and strong consistencies as wellas the asymptotic normality. Then, we present the results of the global weak and strong consistencies using uniform andL1norms. We illustrate this on three types of lognormal kernels estimators. Subsequently, we study the minimaxproperties of the continuous associated kernel estimators. We first describe the model and we give the technicalassumptions with which we work. Then we present our results that we apply on some non-classical associated kernelsmore precisely beta, gamma and lognormal kernel estimators. Finally, we combine continuous and discrete associatedkernels for defining the mixed associated kernels. Using the tools of the unification of discrete and continuous analysis,we show the different properties of the mixed associated kernel estimators. All through this work, we choose thesmoothing parameter using the least squares cross-validation method
Dridi, Zoulikha. "Les propriétés structurales et électroniques des alliages AlxGa1-xN, InxGa1-xN, et InxAl1-xN : étude par la méthode ab initio des ondes planes augmentées avec linéarisation et potentiel total". Caen, 2003. http://www.theses.fr/2003CAEN2076.
Nour, Safouh. "Développements de la méthode MS-LSD vers le calcul de la structure électronique d'agrégats contenant des atomes lourds et des semiconducteurs". Lyon 1, 1991. http://www.theses.fr/1991LYO19009.
Schmitt, Thierry. "Modélisation des transferts acoustiques en moyennes et hautes fréquences par méthode énergétique : application à l'encapsulage des compartiments moteurs". Ecully, Ecole centrale de Lyon, 2004. http://bibli.ec-lyon.fr/exl-doc/tschmitt.pdf.
In order to respect European legislation and requirements in term of comfort, automobile suppliers must have access to reliable vibroacoustic analysis tools. Finite and Boundary Element Methods become inaccurate as the analysis frequency range increases and particularly in the range of maximum human ear sensitivity (5-10 kHz). Such acoustic fields can better be described by global methods such as Statistical Energy Analysis or Sabine's Diffuse Field Theory and more precisely, starting from the local energy balance, by th Simplified Energy Method. This method has been extended in order to take into account ground effects and diffraction involved in the case of an engine compartment. Experiments have shown that diffraction effects can be neglected and that a semi-diffuse reflection model on the ground seems appropriate
Rebei, Mohamed Amine. "Développement de méthode d'optimisation topologique adaptée aux écoulements en régime turbulent : application au cas des échangeurs de chaleur". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM061.
Topology optimization is used in fluid mechanics in order to compute optimal geometry for fluid conduits with respect to objective functions and constraints while allowing more freedom than shape optimization methods. This work offers a solution for such an optimization problem while taking into account turbulent flow and heat transfer. To do so, the turbulence model is modified. The topology problem is implemented as follows. The density method is used to define the solid/fluid distribution. The turbulence and energy model is applied with modifications to take into account the density. The gradient is defined using the continuous adjoint method which creates a set of adjoint equations to solve. At the end, the optimized solution allows us to combine turbulence with convective and conductive heat transfer. We present and apply the method. An analysis of the results is then provided in order to explain the effects of the new formulation on the optimized geometries
Clément, Valérie. "Mise au point et validation d'une méthode quantitative pour évaluer le nombre de copies de régions chromosomiques spécifiques (CNV) dans de grands échantillons". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/27987/27987.pdf.
Mehadji, Chérifa. "Développement de la méthode MS-LSD vers le calcul de la structure électronique de molécules ellipsoïdales et des structures fines d'absorption de rayons X près du seuil". Lyon 1, 1991. http://www.theses.fr/1991LYO10137.
Vidal, Bastías Marcia. "Modélisation du pressage à chaud des panneaux de fibres de bois (MDF) par la méthode des éléments finis". Doctoral thesis, Université Laval, 2006. http://hdl.handle.net/20.500.11794/18667.
This study describes a mathematical-physical model to predict temperature, gas pressure and moisture content during MDF hot pressing in batch and continuous processes. The final system is composed of three differential equations: gas conservation, water vapor conservation and energy conservation. This model introduced the moisture diffusion term which was not considered in the basis model. The system of equations was solved by the finite element method using the MEF++ software developed by the GIREF at Laval University. The boundary conditions used during simulation are of the Neumann or Dirichlet type depending on the process considered. In order to validate the numerical results in 2-D and 3-D, we compared them with experimental data obtained from the batch process in the pressing laboratory and from the continuous process in an industry. For this purpose, MDF panels of black spruce (Picea mariana (Mill.) BPS) were manufactured and temperature measurements made using thermocouples on the surface and the center of the mat. The gas pressure was also measured using a pressure probe located inside the mat. Moreover, in order to evaluate moisture content, seven sorption models were extrapolated and compared with experimental values from the literature. The Malmquist model gives the best correspondence for the relative humidities considered and was therefore used. The numerical results indicate that the predicted temperature, moisture content and gas pressure are in agreement with experimental results for the two processes considered without using an adjustment factor. We concluded that the mathematical-physical model and the finite element method have a great potential to solve this type of problem to control the quality of panels and the losses during manufacturing. It is strongly recommended to look further into research on the values of the physical parameters involved in this process.
Marsal, Philippe. "Etude théorique des paramètres de la résonance paramagnétique électronique par la méthode de la fonctionnelle de la densite". Aix-Marseille 1, 2002. http://www.theses.fr/2002AIX11067.
Machkour, Deshayes Nadia. "Méthode de déconvolution appliquée à l'étude de la densité surfacique d'un arc électrique de coupure basse tension à partir de mesures magnétiques". Clermont-Ferrand 2, 2003. http://www.theses.fr/2003CLF22456.
Amegble, Koami Dzigbodi. "Tests non paramétriques de spécification pour densité conditionnelle : application à des modèles de choix discret". Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/25773.
Dans ce travail, nous étudions la performance statistique (taille et puissance) en échantillon fini de deux tests non paramétriques de spécification pour densité conditionnelle proposés par Fan et al. (2006) et Li et Racine (2013). Ces tests permettent de vérifier si les probabilités conditionnelles postulées dans les modèles de choix discret (logit/probit multinomial à effets fixes ou aléatoires, estimateur de Klein et Spady (1993), etc) représentent correctement les choix observés. Par rapport aux tests existants, cette approche a l’avantage d’offrir une forme fonctionnelle flexible alternative au modèle paramétrique lorsque ce dernier se révèle mal spécifié. Ce modèle alternatif est directement issu de la procédure de test et il correspond au modèle non contraint obtenu par des produits de noyaux continus et discrets. Les deux tests explorés ont une puissance en échantillon fini supérieure aux tests existants. Cette performance accrue s’obtient en combinant une procédure bootstrap et l’utilisation de paramètres de lissage des fonctions noyaux par validation croisée par les moindres carrés. Dans notre application, nous parallélisons les calculs de taille et de puissance, ainsi que l’estimation des fenêtres de lissage, sur un serveur multi-processeurs (Colosse, de Calcul Québec). Nous utilisons des routines "Open MPI" pré-implémentées dans R. Par rapport aux simulations effectuées dans les articles originaux, nous postulons des modèles plus proches de ceux habituellement utilisés dans la recherche appliquée (logit et probit à variance unitaire notamment). Les résultats des simulations confirment les bonnes taille et puissance des tests en échantillon fini. Par contre, les gains additionnels de puissance de la statistique lissée proposée par Li et Racine (2013) se révèlent négligeables dans nos simulations. Mots clés : Bootstrap, choix discret, densité conditionnelle, Monte Carlo, produit de noyaux, puissance, taille.
Hoang, Minh Tan. "Modélisation et simulation multi-échelle et multi-physique du comportement acoustique de milieux poroélastiques : application aux mousses de faible densité". Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1136/document.
This work aims at determining the acoustical properties of poro-elastic media through a multi-scale method. Some imaging techniques (tomography and micrographs) allow to estimate some quantitative microstructure properties of foams containing open or partially closed cells. These properties are used in order to clarify the features of a representative three-dimensional unit cell of a periodic structure, which mimics the behaviour of the real foam. All parameters controlling the acoustical properties of the porous foam are obtained by using the homogenization of periodic structures. In a first step, the structure of the foam is assumed to be rigid. It was shown that, in the case of a narrow distribution of the characteristic size of the local geometry, a direct computation of the macroscopic behaviour from the local geometrical properties is consistent with the measured acoustical properties. For a wide distribution of pore size, the acoustical behaviour is controlled by critical sizes that are obtained from porosity and static permeability for an open-cell foam, while for partially closed cells, the identification of a complementary characteristic dimension within the pores becomes necessary (e.g. closure rate of membranes). Our results compare well with data obtained from an impedance tube set-up. In a second step, effective elastic properties are computed through a modelling of the foam structure by finite elements. The computed elastic parameters are finally compared with data coming from the literature and with results of mechanical tests
Satiramatekul, Thitipong. "Contribution à la modélisation de l'aimantation des brins supraconducteurs". Paris 11, 2005. http://www.theses.fr/2005PA112228.
In the Large Hadron Collider (LHC) main magnets, persistent currents distribution in the superconducting filaments determine the quality of magnetic field. A total image of this currents distribution is the value of the magnetization. It is thus necessary to examine the magnetization of these superconducting filaments during the manufacturing process of the superconducting strands. The prediction of the magnetization can be based on numerical solutions obtained by using the finite element method. In addition, this method makes it possible to determine the influence of the geometrical parameters of the strand on the value of the magnetization. In this work, we have thus developed a finite element code allowing the modeling of several superconducting filaments by taking account of the effects of coupling. This code also integrates the dependence of the critical current density on the magnetic induction. The influence of the space between filaments and of the conductive matrix on the magnetization has been considered. At the end of this work, we have studied the case of twisted filaments
Magalhães, Nelo. "Validation croisée et pénalisation pour l'estimation de densité". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112100/document.
This thesis takes place in the density estimation setting from a nonparametric and nonasymptotic point of view. It concerns the statistical algorithm selection problem which generalizes, among others, the problem of model and bandwidth selection. We study classical procedures, such as penalization or resampling procedures (in particular V-fold cross-validation), which evaluate an algorithm by estimating its risk. We provide, thanks to concentration inequalities, an optimal penalty for selecting a linear estimator and we prove oracle inequalities and adaptative properties for resampling procedures. Moreover, new resampling procedure, based on estimator comparison by the mean of robust tests, is introduced as an alternative to procedures relying on the unbiased risk estimation principle. A second goal of this work is to compare these procedures from a theoretical point of view and to understand the role of V for V-fold penalization. We validate these theoretical results on empirical studies
Cladière, Jean-Luc. "Modélisation de la réactivité de molécules inhibitrices de la thermo-oxydation du polyisoprène : Etude réalisée par la méthode de la fonctionnelle de la densité". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2003. http://tel.archives-ouvertes.fr/tel-00660600.
Meziane-El, May Hédia. "Extension de la régression classique à des problèmes typologiques et présentation de la "méthode des tranches de densité" : une approche basée sur la percolation". Aix-Marseille 3, 1991. http://www.theses.fr/1991AIX32000.
We are about to tackle hereafter the problem of generalizing the regression concept for the purpose of taking into account the data's structural aspects. The resolutions of this matter of fact are mostly overlooked although taking them into consideration would allow a better understanding of a great number of phenomenons and would lead to the establishment of more adequate models. In addition ot the outliers, some other fundamental factors may undermine as well the quality of the models. These factors are structural in nature. Therefore our objctive is to show that from the same set of data, it is possible to search automatically one or even several resulting models. We propose, within this thesis, a method of resoulution that should be both simple and efficient: "the method of density slices", which aim is to find underlying "multimodels" when one is handling heterogeneous data. This method treis to synthesize regression and classification techniques. The non-hierarchical classification of data must be guided by the "percolation principle" and has to be realized simultaneously with the computation of the regression hyperplans. The percolation principle which aims to find the strong density points, has to be applied to slices of points and no longer to individual points. The basis of this method are discussed herewith, an algorithm and some results are presented as well
Dumas, Christian. "Étude cristallographique de l'arginine kinase du muscle de Homarus vulgaris à 3 Å de résolution : application d'une méthode de modification de la densité électronique". Paris 11, 1988. http://www.theses.fr/1988PA112244.